| PSI | the 23rd letter of the Greek alphabet |
|---|---|
| PSI | a unit of pressure |
| PSI | a neutral meson with a large mass |
| PSI | guavas |
| PSI | small tropical shrubby tree bearing deep red oval fruit |
| PSI | small tropical American shrubby tree |
| PSI | South American tree having fruit similar to the true guava |
| PSI | small tropical shrubby tree bearing small yellowish fruit |
| PSI | small tropical shrubby tree bearing deep red oval fruit |
| PSI | a hallucinogenic compound obtained from a mushroom |
| PSI | a hallucinogenic compound obtained from a mushroom |
| PSI | a mineral consisting of hydrated basic oxide of manganese and barium |